Conventionally, in the form of production by order without performing speculative production, ordered items are divided into manufacturing order, and from the viewpoints of on-time delivery performance, the equipment operation rate, the intermediate inventory volume, cost and the like, the production schedule is created. As the methods for creating the above described production schedule, two methods are used, when these methods are broadly divided technically.
Namely, as disclosed in, for example, “Method and system for evaluating production scheduling” of Patent Document 1, the first method is the method in which in a simulation imitating the plant, built on a computer, operation of real devices is predicted by using the information acquired from the same interface as the real devices, and based on the operation prediction, virtual production is performed at a higher speed than the real devices, and by presenting highly accurate indexes by using the process and result of the virtual production, evaluation and selection of production schedule are made possible.
As disclosed in “Products distribution scheduling device” of Patent Document 2, the second method is the method in which a schedule is created based on the methods which ensure optimality, such as linear programming, and mathematical programming.
As disclosed in “Method and system for evaluating production scheduling” disclosed in Patent Document 1, the method for creating a production schedule by using a simulator (1) needs to perform simulation by variously changing the conditions and repeat the evaluation of the results many times, until the satisfactory result is obtained. Therefore, it (2) has the problem of requiring much time for creating the production schedule in a large-scale plant. Further, it (3) has the problem that the simulation rule has to be set in detail to obtain a highly accurate production schedule.
As disclosed in “Product distribution scheduling device” of Patent Document 2, the method for creating a schedule based on the methods ensuring optimality, such as linear programming and mathematical programming has (1) the problem that as the scale on which the production schedule is created becomes large, it is difficult to obtain solution within a practical time period. Further, an error is caused by the constraint and condition which cannot be expressed in mathematical expression, and therefore, it is not certain whether the obtained production schedule is executable or not.
In view of the above described problems, it is an object of the present invention to make it possible to create a production schedule assured to be actually usable in a target production process for schedule creation by making it possible to obtain an optimum production simulation result without repeatedly performing simulation.
Patent Document 1: Japanese Patent Application Laid-open No. 2002-366219
Patent Document 2: Japanese Patent Application Laid-open No. 2000-172745